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Saturday, March 3, 2012

Understanding Military Geography - The Battle of Manassas/Bull Run Geographic Analysis

I thought I’d begin today with an entry on military
geography, specifically how geography played a huge role and affected the
battles of Manassas/Bull Run during the Civil War era in the United States. In 1861, the
United States broke out into a Civil War between northerners and southerners
that led to many battles and skirmishes which carried on for several
years. This war was based on
geopolitical reasons that led to the South wanting to break away from the Union. The specific
emphasis of this posting will be on the first and second battles of Manassas. The first battle began in July 1861, and was
one of the main battles with land forces.
It would shape the following battles of the war between the Confederate
(south) and the Union (north). The second battle began in August 1862 with
the hopes that the Union could claim victory and take control of Richmond. However, both battles contributed to a
Confederate victory mainly due to the geographic expertise of the involved Confederate
generals; as well as the lack of geographic expertise and poor organizational
skills of the Union generals. Furthermore,
both armies thought these battles would be easy victories that would end the
war early. Historically, this was not
the case, and more battles continued to unfold throughout the following years.

It is important to recognize
the geographical factors that assisted in altering both outcomes. Knowing the lay of the land is a very
important factor when engaging in war because it will ultimately determine
planning, operational, and tactical stages of a war. For this to actually matter, generals and
commanders must fully utilize their geographic resources to gain an advantage
over their enemy. The geography of an
area influences choke points, order of battle organization, key routes,
defensive positioning, and offensive positioning. In this posting, I will describe the geographic
basis for both battles; and indentify how key geographic features played an
effective role in determining the course and outcome of both battles.

CIVIL WAR MAP RESOURCES

For the purpose of this posting,
the Prince William County corridor (between the Bull Run/Pond Mountains and
Bull Run creek) will be the main focus of geographical study, and the main location
for the battles. Nevertheless, the two
campaigns actually began and ended well past these boundaries in the Virginian
counties of Culpeper, Rappahannock, Fauquier, and Fairfax.

Figure 1. I created this map using ArcGIS 9.3 and it depicts thePrince William Corridor. The significant locations of the the battles arelayered over a modern-day topographical map in order to understand therelation between the points. This map uses the WGS1984 datum.

Maps during this era were not
easily obtainable and not well organized compared to today’s standards of
cartography. Most maps used by commanders
during the Civil War were usually hand-drawn and were restricted to specific
areas of interest.This poses potential problems and
benefits for the military. The problems
result from the limited vision of only looking at the immediate area. In order to understand the complete benefits
of a map, an overview is needed to look at the bigger picture. Obstacles may pose threats if they are not
depicted on a map prior to utilizing a route to gain access to the specific
area of interest. Evacuation routes or
choke points may be difficult to plan if a commander is walking into the
unknown and may be surprised by an ambush or a dead-end. In addition, the maps were not always
reliable. Based on my observations, relative
distance was most likely incorporated in to most maps of this time which does
not rely on accuracy because it is not mathematically represented within a
scale or a map projection.

The beneficial part of a map
catering to a specific location is the increased knowledge of a commander to
gain insight on where their offensive and defensive position will be placed in
order to maximize their chance of success.
Although in regards to the aforementioned problems, the maps used for
the battles of Manassas
were mainly guides and were not designed to be taken literally. The Union army presumably recognized these
problems and decided to venture into establishing a balloon corps which would
provide mapping and intelligence to the Union commanders. This type of aerial surveillance provided the
Union commanders with information regarding the terrain, lines of
communication, and Confederate army order of battle/movement in the regions of
Virginia being observed.

The Union’s first opportunity
to use the balloons was in the first battle of Manassas, where Thaddeus Lowe
launched his first balloon, “Enterprise,” from Alexandria to observe enemy
movement and map out the terrain of Northern Virginia.However, problems arose
with the use of this balloon due to various mechanical problems and lack of
untrained aeronauts. Eventually, in
1862, aerial surveillance became fully operational and was able to examine
geographic areas. This type of
geospatial intelligence may have assisted General John Pope of the Union in
examining Confederate movements around Bull Run; however, due to contradictory
intelligence reports from Washington,
D.C., they did not prove to be as
useful as they could have been. As a
result, these various reports most likely created confusion among the Union generals
in the second battle of Manassas.

GEOGRAPHIC OVERVIEW

The topography of the Prince
William corridor is mountainous in the west and subsides in elevation in the
east. The central and eastern part of
the corridor is consumed by rolling hills, forests, ridges, and farmland. The major mountain range in this region is
the Blue Ridge Mountains and has bands
stretching southwest to northeast. The
easternmost band of the mountain range is named the Bull
RunMountains and
travels from the RappahannockRiver northeast to Maryland.
The Bull RunMountains are located at
the western part of the Prince William corridor. The southern portion of the Bull RunMountains
where the ridgeline descends is called the PondMountains. The descent, also known as Thoroughfare Gap,
is the only area for many miles that can be easily passed through the mountain
chain because these mountains have sharp and rugged ridges that are
impassible. Besides the mountains, the
remainder of the corridor consists of smaller, non-protrusive ridges and hills
which do not impede soldier movement significantly. The following key features in this part of
the corridor are as follows: Chinn Ridge, Henry Hill, and Matthew’s Hill which
all have an elevation of approximately 280 feet above sea level, and Stony
Ridge which was approximately 335 feet above sea level.

Figure 2: This photograph was taken from the west side of the Thoroughfare Gap (central). The Bull Run Mountains are on the left and the Pond Mountains are on the right side of the photograph.

The geology of this area has
laid the framework for the terrain and ultimately has allowed each side to take
advantage of concealment techniques. The
majority of the battles were fought in the lower elevations in an area known as
the CulpeperBasin.
At the base of the Bull
RunMountains
is a minor fault line which during the Mesozoic era ruptured and formed a break
in the rocks. This contributed to the
basin changing the landscape from rugged terrains to rolling hills.Sedimentary rocks make up most of the
corridor with siltstone that may be overlaid with red and gray shale. In addition, the sedimentary rocks created
open and smoother terrain which is beneficial for transportation networks and
agriculture. Most of the soil around the
actual battlefield had not been through metamorphosis; therefore it also
created a suitable area for farming and increased trafficability. West of the fault line is diabase, which are
rocks that have many dark and clay minerals providing many nutrients for
vegetation to flourish. These types of
rocks are hard; and have an excellent resistance to erosion which allows rugged
terrain and ridges to be formed.Stony Ridge, which was formed at the end
of the diabase, is extremely important for tactical purposes and lies in a
wooded area. This ridge proved to be a
viable cover for the Confederacy in the second battle of Manassas.

The hydrography of the area is plentiful and provides
many offensive and defensive tactics for the soldiers of both battles. Mainly fords and creeks were used as barriers,
crossing points, routes; thus providing important, strategic factors for
soldier movement. Most of the creeks ran
southeast towards the Chesapeake Bay. The three most significant creeks that influenced
both the Confederate and Union soldiers were Bull Run,
Broad Run, and Dogan Run. Fords along
these creeks became key geographic areas for the battles. In my opinion, the troops that controlled the
fords would increase their soldier movement, and optimize their offensive
battle tactics in order to attack their opponents’ flanks with ease.

Lines of communication in the Prince William corridor
provided support to the armies of the battle at multiple levels: strategic,
tactical, and operational. There were
several key roads and railways that contributed to the battle. The following lines of communication were
observed upon my field visit to the battlefield. Key roads were used to assist the soldiers on
both sides in their navigation from one point to another point for long
distances. Roads were also used as
reference points to assist troop movement between the different local areas of
battle such as prominent hills and ridges.
Some of these key roads were Warrenton Turnpike (Route 29) which was
located between Thoroughfare Gap and Centreville in an east/west
direction. The Manassas-Sudley Road was located between
the hamlet of Sudley and Manassas Junction in a north/south direction. Lastly, the Groveton-Sudley Road was located between
Sudley and the hamlet of Groveton in a north/south direction. In addition to the Warrenton Turnpike which
interconnected multiple counties, there were also two prominent railways that
led the armies to the corridor. The
first railroad was the Orange & Alexandria (O&A) Railroad which ran between Culpeper
and Alexandria, Virginia.
The second railway was the Manassas Gap Railroad which ran between Front
Royal, Virginia and Manassas Junction.
There was a third railway that began construction prior to the war;
however, due to a lack of funding, the railroad was unfinished during both
battles. The unfinished railroad was
located slightly southeast of Stony Ridge and became very beneficial to the
Confederate army in the second battle because of the concealed position it
offered the soldiers.

FIRST BATTLE OF MANASSAS

Preparations among Union
and Confederate commanders were beginning for what would be considered the
first Battle of Manassas. The majority
of Confederate armies traveled slightly north of Richmond to the battlefield area by several routes
and modes of transportation. The
Confederate infantry traveled by train, while the Confederate cavalry and
artillery took advantage of several major roadways to the battlefield site. Other Confederate soldiers traveled from the Shenandoah Valley in the west via Manassas Gap
Railroad. The Union armies mostly
traveled west from various locations in FairfaxCounty and along the Potomac
River.

Upon arrival to the battlefield on July 16, 1861, the
Confederate army defensively positioned themselves along several key choke
points on the western side of Bull Run because of their familiarity with the
terrain. General P.G.T. Beauregard
sought out these positions based on intelligence reports that Union forces were
headed towards Bull Run. Several fords and bridges along an
approximate 2.5 mile radius of Bull Run were
then guarded by Beauregard’s forces. One
of the key choke points was StoneBridge which was a flat bridge that carried Warrenton
Turnpike over Bull Run. Just to the south of the bridge were Ball’s
Ford, Lewis Ford, and Island Ford which were all key crossing points from FairfaxCounty into the Prince William
corridor.

Union forces had identified that the barrier Confederate
forces established became an unwanted obstacle for the Union movement;
therefore, they diverted their route in a northwesterly direction to a crossing
point that was not being guarded by the Confederates approximately 2 miles
north of Stone Bridge. This crossing point was known as Sudley Springs
Ford. The geographic prominence of this
point provided an opportunity for the Union to surprise attack the
Confederate’s flank in addition to blindsiding them from the rear since their
attention was faced towards Bull Run. This ford was a slow-moving, shallow
crossing that made it ideal for wagons and artillery to pass through thus
allowing the Union soldiers to stay dry.

Confederate forces became aware of the Union’s
diversion and moved north to intercept them as they were traveling south from
the hamlet of Sudley. Both forces came
to a halt at Matthew’s Hill when the Confederate forces moved into secured
positions about 250 yards from the top of the hill on the southern slope.This
was a key opportunity for the Confederate forces because the reverse side of
the hill provided concealment against enemy fire. When both forces finally initiated the first
battle on Matthew’s Hill, it was then realized by the Confederate generals that
once on top of the hill, the hill did not provide any real geographic advantage
since the top of the hill was open ground.
As a result, the Confederate forces retreated because of the lack of a
geographic advantage and their disorganized lines. They then relocated to Henry Hill, just south
of Matthew’s Hill, in order to regroup.
Meanwhile, the Union soldiers seized Matthew’s Hill and dispersed some
of their forces to an adjacent location named Dogan Ridge.

Henry Hill was
situated approximately 1,200 yards west of Bull Run. The Confederate armies had a clear view of
the Union forces from here if they attempted to retreat over StoneBridge. The foreground of the hill was open fields
that overlooked a creek to the north named Young’s Branch. On the other side of the creek, the terrain elevated
to form Buck Hill, which was only a quarter of a mile from the top of Matthew’s
Hill. Both armies stood their ground on
top of each of the hills in order to regroup.
Once again, the Confederate army’s position on the reverse slope of the
hill provided protection from direct fire.
When the Union forces approached Henry Hill, the Confederate army
encroached onto the higher ground and showered the Union forces with
gunfire. The Confederate leverage over
the Union assisted them with a huge vantage
point in the overall battle. The
Confederates continued to hold their position and did not allow Union forces to
charge up the slope of the hill. The
foreground of Henry Hill was open and treeless, but the fluctuation of small
elevation made the Union’s maneuverability difficult because of its uneven
grade. The Confederates also used a tree
line on the hill for concealment; thus leaving 400 yards of farmland and fields
in front of them to devastate the Union army.
Eventually, the Union troops diverted their forces to an adjacent,
higher elevation location, named Chinn Ridge.

Chinn Ridge provided
more suitable cover for both armies in this part of the battle. The Union forces used the forested lower
level of the ridge named Chinn Branch for concealment when diverting their forces
and the Confederate forces also used them when they were in pursuit of the
Union forces. The purpose of the entire
battle shifting to another key geographic feature was for the Union
to gain a geographic advantage over the Confederate forces; however, some of the
Confederate forces were still at the base of Henry Hill at the time of the
diversion. This new strategy consisted
of Union forces moving southward on the peak elevation of Chinn Ridge and then
cutting eastward in order to strike the Confederate’s right flank on Henry Hill.
Subsequently, the Union forces were not
aware of where the Confederate lines were specifically located. This became the Union’s
ultimate failure.

Due to disorganization in the Union forces, the majority
of Confederate forces had shifted their position from Henry Hill and pursued
the Union as they climbed uphill on Chinn
Ridge. This pursuit surprised the Union
forces on the ridge and then forced the Union forces to reverse their line
northwest of their previous position. Unfortunately,
the Union strategy to attack the Confederate’s on Henry Hill by forming a line
in the forests of Chinn Branch and Bald Hill never happened. The result was a Union army that retreated
back to Centreville (located on the eastern side of Bull
Run), and lost this battle.
The Confederate army positioned themselves nearby to Stone Bridge in
order to cut off the retreating Union forces; however, the Union retreated back
to their entry route via Sudley Springs Ford.

SECOND BATTLE OF MANASSAS

Nearly a year after the first Battle of Manassas, another
battle in the same area was brewing.
Confederate armies began to set up their strategic plan of attack with
the use of geographic intelligence gathered by General Thomas “Stonewall” Jackson. He was able to determine exactly where to
establish a defensive line. The
Confederate and Union armies advanced to the
Prince William Corridor, from multiple directions. The Confederates mainly traveled through the
Blue Ridge Mountains from Richmond. This strategic area provided concealment and
allowed for a safe trip to the battlefield site. They traveled on paths through forests, open
fields, and mountainous terrain until the reached Thoroughfare Gap.

The first Confederate force, led by General Jackson,
passed through the Gap and used Broad Run as a navigational guide to the O
& A Railroad which intersected at Bristow.
The Confederates realized this was a vital choke point for the Union
army and decided to destroy a railroad bridge at the intersection of the
railway and creek, as well as ripping up the tracks to ensure the Union forces
could not use this line of communication.
In addition, these forces traveled several miles northeast along the
railway and demolished the Union supply depot at Manassas Junction. This was a devastating blow to the Union army
because it hindered their military movement, communications, and logistics for
the battle. In the meantime, several
Union forces attempted to travel to Manassas
via the south and east, but were slowed down due to much disorganization. This provided the Confederate forces to
appropriately position themselves in geographic prominent areas within the
Prince William corridor.

The Confederate forces traveled back to Thoroughfare Gap
after the destruction which occurred at Manassas Junction. Since the Gap was located in between the Bull
Run and PondMountains, it provided protection for
the Confederate army. The only direction
which the Union forces would be able to approach them was from the east which
left the Union forces without option to attack any of their other flanks. As a result, the Gap became a tactical
advantage and it was realized that whoever controlled the Gap, controlled the
battle. Eventually, more Confederate
forces arrived at the Gap. They
positioned themselves on the western part of the Gap and waited for the Union
forces coming from the eastern opening, while other Confederate forces
continued on to Stony Ridge to the east.
Shortly thereafter, Union forces arrived at the eastern part of the Gap
and barricaded the entrance leading out to the CulpeperBasin. In the wooden areas surrounding the Gap’s
entrance, Union forces cut down trees and made the Gap impassible for
Confederate forces, which ultimately did slow them down. In less than 24 hours later, the Confederates,
along with their artillery, ordnance, and wagons that accompanied them, crossed
through the narrow passage that was barricaded and were able to join their
counterparts at Stony Ridge.

The next vital
geographic area in the battle was at Stony Ridge. It is a ridge that runs southwest to
northeast. On its eastern side away from
the Bull Run Mountains, it is protected by dense forests as well as trenches
and banks that make up the railroad bed that was left unfinished prior to the
Civil War. The original Confederate
forces that destroyed the depot at Manassas Junction and left the Gap before
Union forces blocked it traveled to the Stony Ridge area to establish a
defensive line as well as a hideout.
This location was ideal for the soldiers because the forest provided
concealment, and leverage due to the elevation.
Also, an unfinished railroad provided a 100-foot deep depression in the
ground which allowed for a surprise attack against the approaching Union
forces. The Ridge also had diabase which
resulted in hard rock and boulders making it tough for Union forces to rush the
Confederate forces.

When the Union forces
finally arrived at the Confederate hideout, the Confederate forces ambushed
them allowing a devastating blow to the Union flanks. The Union
was eventually forced into an open field around a local citizen’s property
named Brawner’s Farm. At this point the
Confederate forces at the Thoroughfare Gap finally arrived on scene and also
attacked the Union forces by way of Warrenton Turnpike. The open field did not provide any advantage
to the Union soldiers as they were not able to fully engage their enemy. In addition, there were still Confederate
soldiers attacking from the unfinished railroad site, and the higher
elevation. The only assistance that the
terrain offered the Union forces was several shallow depressions encased with
streams that were tributaries of Dogan Run.
The streams provided minimal protection since they were on the lower
ground. Some of the soldiers on both
sides ran out of ammunition and decided to throw superficial, exposed rocks as
a substitute.

As a result, the Union forces were unable to drive the
Confederate forces out from their tactical ground and had no other option but
to pull back further east to Manassas-Sudley
Road. In an attempt to regroup, the majority of
Union forces formed lines along Chinn Ridge, Matthews Hill, and Henry Hill since
the Union leadership was familiar with these locations from the first battle. Their numbers were so small that the
Confederate forces charged them at every angle.
Subsequently, the Union forces did not have any geographic advantage
over the Confederate forces and finally retreated back towards Washington via thick
woods to conceal their departing route; thus the Confederates had achieved
another victory.

CONCLUSION

Overall, the studying of geographic factors of an area is
essential for planning and executing a battle.
The topography, hydrography, geology, and lines of communication all
integrated together to assist in the outcomes of the battles. Ultimately, the Union
failed to execute a successful strategy largely based upon the unknown terrain;
yet, it provided an advantage to the Confederacy. In addition, the Confederate army had the
topographical knowledge and the assistance of local farmers as food sources and
guides. The Blue Ridge Mountains
provided a good majority of natural resources needed for war such as coal for
heat, salt for preserving food, and saltpeter for gunpowder which also gave
them an edge towards victory. However,
both sides became victims of fatigue, disorganization, and insufficient
ammunition supply.

Confederate forces used geography to their advantage by
pushing the Union troops back towards a retreat in both battles.On
the other hand, the Union commanders approximated the location of the
Confederate army erroneously which resulted in failing results for the Union.Victories
are determined by many factors, but the main factor relies heavily on the
geographic prominence and attributes that militaries use for an advantage, as
the battles of Manassas
proved. Lastly, the battles at Manassas set the pace for
modern geographic intelligence through aerial surveillance. This assessment on the geographic factors
that affected the outcomes of the battles is a prime example of what happens to
an army when they do not have accurate information regarding the geography of
an area. It ultimately results in a win
or loss. As a result, U.S. engineers
embarked on huge mapping projects after the first battle for these reasons in
order to obtain better geographic intelligence.
Today, our nation stands on the forefront of the world by producing the
most vital geographic intelligence because of technological advances in aerial
and space surveillance. For these reasons,
geography played an effective role in determining the course and outcome of
both battles in Manassas,
as well as the battles occurring overseas every day.

References:

Boyne, W. J. (2003). The influence of air power
upon history. Gretna:
Pelican Publishing

Company.

Collins, J. M. (1998). Military
geography for professionals and the public. Washington, DC: National
Defense University Press.

Gottfried, B. M. (2009). The
maps of First Bull Run: An atlas of the First Bull Run (Manassas) Campaign,
including the Battle of Ball's Bluff, June-October 1861. El Dorado Hills, Calif:
Savas Beatie.